Computing device



. UNITED STATES PATENT torsion.

specincation of Letters Patent.

Patented March 6, 1906.

Application llod Augnlt 18, 1905.` Serial No. 274,691.

To all whom it may concern:

' Be it known that' I, WILLIAM H. WATSON, a citizenof the United States,residing at Danvers, county of Essex, State of Massachusetts,

- -have invented a certain new and useful Im.

- provement in ComputingDevices, of which the following is aspecification,

reference being had therein to the accompanying draws. miltly inventionhasfor its object to rovide a convenient device by means of whic averaesand proportions may be computed rapand Without figurlng.

Ihe device is especiallyr adaptedl for use where it is desired to strikean, average between two numbers or where it is desired to find the averae .between two numbers one of which `is to e given a greater weight thanthe other-as, for instance, where a teacher has to compute a scholarsmarks and desires to give the mark on the daily recitations three timesthe weight which it is desired to giveto the mark obtained by the pu ilupon the examination. If, for instance, t e pupil has obtained a` markfor the recitations of 84 and a mark for the examination of 96 and it isdesired to give recitations three times the Weight of theexamination itis found that the desired average is 87.

B,whic

M invention will be fully understood from the ollowing'description,taken in connection with the accom .anying drawings, and the novelfeatures t ereof are pointed out andv clearly defined in the claims atthe close of this s ecification.

Re erring now to the drawings, Figure lis a plan view of a deviceembodyi my invention. Fig. 2 is a side elevation t ereof. Fig. 3 is aplan view of the fixed card. Fig. 4 is a plan view of the movable card.

Referring now to the drawings, at A is rindicated a card, which forconvenience I have called thefixed card, and which may be made of anyconvenient substance-as, for instance, cardboard or celluloid. U on thiscard is ivoted at its center a movalile card li is circular in shape andis somewhat smaller than the fixed card A. It is necessa that the cardsA and B be movable each wit relation to the other; but I have designatedthem by the terms fixed and movable to distinguish them. The movable-card B is provided with a handle C, by means of which It may be rotatedabout the central pivot D. Slots E, F, Gr, and H are cut in the saidmovable card B'to ermit the user to see certain figures on the ed card,as Awill be later described.

In the drawings I have shown Iny device as adapted especially for use inaveraging percentages, and as the percentages below thirty areordinarily neghrihle in the work. for which my computing evice `isintended and as the comparative weights to be given to the numbers to-be averaged are usually one toone, one to two, one to three', and oneto four I have shown in thedrawings a computing device ada ted for thisparticular work; but it isto e understood, of course, that the inventionmay be embodied in other forms arranged for use where other properetions or sets of numbers are required.

Upon 'the fixed card A and at a distance from its center about equal tothe radius of the movable card B, I divide a convenient arc of a circleinto equal spaces, numbered from 30 to 100, as indicated at I. Forconvenience I have denominated this are the greater-weight Scale.

The circumference of the movable card B is similarly divided into arcs,which I denominate the lesser-weight Scales. Each of these scales, whichare indicated by the lreference characters J, K,' L, and M, are dividedinto equal spaces numbered from thirty to one hundred, in the samemanner as has been described in connection with the geater-Weight scaleI on the fixed card A. he lesser-weight scales have a lengthproportionate to the length of the greaterweight scale and to therelative Weights to 'be given to the numbers to be averaged. 'lhus thescale K is one-half the length of the scale J, the numbers to beaveraged by the use of this scale being give-n the comparative weight ofone to two. The length of the lesserweight Scale L is one-thir thelength of the mater-weight scale I, and the length lof the esser-weig tScale M is one-fourth ofl the len rth of the greater-weight scale I,thesesca es being used for yproportions of one to three and, one tofour. By choosing a right length for the are occupied by the scale I andusing the proportions mentioned the lengths of the four lesser-weightscales occupy the entire circumference ofthe .movable card B. It willthus be seen that the arc occupied bv the scales J, K, L, and Mcontains, respectively, one hundred and seventy-two and fourif the,'eighty-six and two-fifths, fiftyseven and IOO so long as tthree-fifths, and forty-three and one-iifthdegrees.

Concentric with the greater-weight scale I and nearer to the center ofthe iixed cardA are arranged what I denominate resultscales, one foreach of the different proportions on the basis of which the averages areto be computed. These result-scales are indicated by the referencecharacters N, O, P, and Q, res ectively, and correspond to thelesser-wei t scales J, K, L, and M, respectively. liach of theseresult-scales has a length in de rees equal to the length of thereater-Weigt scale plus the length of the esser-weight scale to whichthe result-scale corresponds. Thus the result-scale N has a length equalto the length of the greater- Weight scale I plus the length of thelesserweight scale K, to which the result-scaleV N corresponds, and theresult-scale Q has a length e ual to the greater-wei ht scale I plus theength of the lesser-weig t scale M, to which the result-scale Q corresonds.

The result-scales N, O, P, an Q are located at radial distances from thecenten of the iixed card A equal to the radial distances of the holes orslots E, F, G, and H, so that when the movable card B is revolved aboutits'pivot certain of thefi ures and divisionlines of the sets of scalesO, P, and Q appear and are visible through their respective slots E, F,G, and H. I provide each of the said slots or holes E, F, G, and H withindicating marks or pointers R, S, T, and U, re-' spectively, each ofthe said pointers being located in the middle of the lesser-weight scaleto which it ap lies.

I find it convenient to locate the resultscales symmetricall of themedian line 4 4 of the greater-Weig t scale and to place the ointers onthe movable card on the median ines of the arcs of the lesser-weightscales to which their7 apply; but this is not necessary e pointer on themovable card bears the same relation to the position of thelesser-Weightfscale as the result-scale does to the position ofthegreater-weight scale.

It is to be noted that fthe divisions'.y on the fixed card A from thirtto one hundred are numbered clockwise, W 'le the divisions on themovable card B are numbered counterclockwise. It is further to be notedthat in this s eciiication I have referred to the lengt of the variousscalesfi By this is to be understood the len th measured in degreeswithout regard to t e radius of the are which forms the scale referredto.

Having now described the manner in which I la out my improved computingdevice, I wil explain the mode of operation by means of WhichI am ableto obtain the averages and proportions.

Let it be su posedthat'it is desired toobtain the simp e average of thetwo numbers 84 and 96. The division-line indicating'the number "84 onthe lesser-weight scale J of the movable card B is placed to coincidewith the division-line corresponding to the number 96 on thegreater-weight scale I on the fixed card. The pointer R will then beseen to point to the division-line corresponding to the number 90 of theresultscale N, this ii ure being seen throu h the slot or aperturecorresponding to theesser- Weight scale which is used-viz., that markedl to 1. If it is desired that the number 96 be given twice the Weight ofthe number 84, the scale K is used instead of the scale J, thedivision-line marked 84 on that scale being placed in registration withthe divisionline corres ondin to 96 on the greaterweight sca e-I. hereadin is then made by means of the pointer S, which is provided for thelesser-weight scale K. The desired result, 92, may be seen through theslot F. In the same manner other-averages may be obtained.

A general rule for the operation of my improved averaging device may bestated as ollows: Find the number to be 'ven the least weight on thelesser-weight sca emarked with the proportion desired, turn the movablecard until the number found coincides with the division-line of thegreater-Weightv scale on the fixed card corres ondi to the other number.Then read t e num er indicated by the pointer for the lesser-weightscale HWhere the first number was found.

Whena simple'avera e isto be found, either number may be foun on thefixed card or' on IOO suit-scale havin alength equal to that of.v

the greater-weig t scale plus the length `of a` lesser-weight scale, alesser-weightscale on the said movable card having a lengthproportionate to the length of the greater-Weight scale and the relativeweight to be given to the two numbers tobe averaged, anda pointer forthe said lesser-weight scale to indicate divisions of said result-scale.

2. In a computing device of the character described the combination witha fixed and movable card of a eater-we' ht scale and-a series ofresult-sca es on the ed card, the said result-scales having a length eual to that of the said greaterweight scale p us the len th 'of acorresponding lesser-weight sca e, lesser-weight scales on the saidmovable card having lengths proportionate to the length of the saidgreater-weight scale and the relative weights to be given the twonumbers to be averaged, and a ointer for each ofthe said lesser-weightsca es.

3. In a computing device of the character described, 'the combinationwith a fixed and lne movable card, of a reater-wei ht scale and a seriesof result-sca es on the ed card, the said result-scales having a lengthe ual to that of the said greater-weight scale us the length of a corresonding lesser-weig t scale, lesser-weight scaies arranged aboutthe eir-lcumference-of the said movable cardhaving len ths proportionate to thelength of the saifI4 greater-weight scale and the relative Weights to begiven to the numbers t'o b e averaged and a ointer on the median line ofeach of the said esser-Weight scales.

4. In a computing device'of the character described, the combinationwith a fixed V,and a movable card, of a greater-weight scale andresult-scales arranged on the fixed card conccntricall with relation to.each other, the said resu t-scales havin a length equal to that of thegreater-Welght scale lus the length of a correspondin lesser-Weig tscale, a lesser-weight scale on te said movable card having a lengthproportionate to the len th of the greater-weight scale and the relativeWeight to be given to the two numbers to be scale are visible, and 4adivislons ofsald result-sca es. v

avera ed, and a ointer to indicate divisions of sai result-sca es.

5. In a computing device of the character described, the comblnationwith a fixed and a movable card, of greater-Weight scale and aresult-scale arranged concentrically with relation to each other, thesaid'result-scale having a. length e ual to that of the greater- Weightscale p us the length of a lesser- Weight scale, a lesser-Weight scaleon the said movable card having Va length proportionate to the lengthofthe greater-welght scale and the relative Weight to be given to `thetwo numbers to be avera ed, slots in the said movable card for eaclesser-Weight `scale through which the divisions of the resultonter toindicate In 'testimony whereof I aHiX my signature in presence of twowitnesses.

` WILLIAM H. WATSON. yWitnesses z' BEssIE G. MoRRrs, GEORGE P. DIKEH

